Deep rolling of crankshaft journal fillets for crankshaft strengthening purposes is well known in the art. The journals of a crankshaft for internal combustion engines are disposed between laterally spaced counterweights formed on the crankshaft. The journal fillets are located at the intersection of the journal and the adjacent counterweight and define concentrated annular areas of high stress which must be mechanically relieved to improve crankshaft strengths in these otherwise weakened areas. Various arrangements of floating jaw units are employed at each journal to mechanically roll the fillets and relieve such stresses and strengthen them.
Generally, each jaw unit has opposing upper and lower jaw arms, which are pivotally connected to one another. The jaw arms have facing jaws that are adapted to close about a journal during the deep rolling operation. A hydraulic cylinder is disposed between the opposing end of the jaw arms and is adapted to open and close the facing jaws about the journal and apply a working force to the fillets. More particularly, the jaw of the upper arm has tooling which includes rollers which engage and mechanically work the journal fillets while the opposing jaw of the lower arm has tooling with support rollers that support the journal during fillet rolling. Accordingly, a portion of each jaw unit and the tooling must be in close proximity to the journal and hence the interfacing side wall of the counterweights or other part of the crankshaft while the journal fillets are being rolled.
Prior to the present invention, a linkage has been operatively connected to the lower arm or jaw to limit any tendency of the jaw assembly to move laterally relative to the journal that, for example, may result from a taper of the journal. However, even with such a linkage, lateral movement may occur to such an extent that the flanks or sides of the counterweights or other adjacent portions of the crankshaft are contacted and abraded by the tools or a portion of the jaw assembly. This may cause crankshaft damage and result in part rejection of the crankshaft and re-machining or scrapping of the part. The fillet rolling tools can also be damaged from such contact during deep rolling resulting in production down time for machine repair and tool replacement.